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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 7 |
| 3 | 35 |
| 4 | 156 |
| 5 | 670 |
| 6 | 2886 |
| 7 | 12797 |
| 8 | 59537 |
| 9 | 294585 |
| 10 | 1562324 |
| 11 | 8900568 |
| 12 | 54346140 |
| 13 | 353937741 |
| 14 | 2444771767 |
| 15 | 17814457447 |
| 16 | 136308242144 |
| 17 | 1091001532590 |
| 18 | 9105746802826 |
| 19 | 79041398643849 |
| 20 | 711994012088297 |
| 21 | 6642697774712213 |
[1,7,35,156,670,2886,12797,59537,294585,1562324, 8900568,54346140,353937741,2444771767,17814457447, 136308242144,1091001532590,9105746802826, 79041398643849,711994012088297,6642697774712213] |